Individuals with hemiparesis following a stroke are left with various degrees of impairment in function, especially affecting their walking ability. This BRP renewal application focuses on developing and testing novel rehabilitation solutions for gait retraining of stroke and other motor-impaired patients. Our rehab solutions consist of un-motorized and motorized exoskeletons, integrated with functional electric stimulation (FES), supplemented by biomechanical models. In the first five years of this project, we showed the feasibility of this approach through development of robotic exoskeletons with limited subject testing. The next five-year goal of this project is to integrate and expand on our current understanding of component science and technologies, i.e., un-motorized and motorized exoskeletons, FES, and biomechanics to fabricate and test novel rehabilitation solutions for gait training of patients with stroke. PUBLIC HEALTH RELEVANCE: The goal of this renewal application is to integrate and expand on our current understanding of component science and technologies, i.e., un-motorized and motorized exoskeletons, FES, and biomechanics. We plan to test novel rehabilitation solutions for gait training of patients with stroke and compare these with currently accepted training methods, such as the body-weight supported treadmill training. The project aims are: Aim 1: Develop bilateral gait rehabilitation systems for treadmill training of hemiparetic stroke patients using un-motorized and motorized exoskeletons and FES. We will fabricate and test the following two rehabilitation systems: (i) Bilateral Gravity Balancing Orthosis (GBO) with FES/Motorized control of the ankle, (ii) Bilateral Active Limb Exoskeleton (ALEX) with FES/Motorized control of the ankle. Novel symbiotic control of the ankle will be implemented where the ankle motor will be used as a safety net for delivery of the FES training. Aim 2: Test the effectiveness of these two rehabilitation solutions in patients with stroke and compare their performances with body weight supported treadmill training (BWSTT), a paradigm used currently in the literature for gait training. Aim 3: Prediction of muscle coordination deficits off-line in individuals with hemiparesis using gait analysis, biomechanics, FES models, and sensors on the exoskeleton. The musculoskeletal models will be used before training, as a screening mechanism, and post-training to understand why a particular gait training strategy with the exoskeleton worked.